Electrical control signal transmission system



Aug. 30, 1966 A. EISERLOH 3,270,263

ELECTRICAL CONTROL SYSTEM TRANSMISSION SYSTEM Filed April 26. 1962 50 L. f: l L I fi M P a 1 $0 -70 I 67 A I a z, 52,520 a 2 g 50 F", l I [22 (55 I if L I (50 Z T I z 32 89 02 301 54 United States Patent "ice 3,270,263 ELECTRHCAL CONTROL SIGNAL TRANS- MISSION SYSTEM Norman A. Eiserloh, Muskegon, Mich, assignor, by

mesne assignments, to Dresser Industries, Inc., Dallas,

Tex., a corporation of Delaware Filed Apr. 26, 1962, Ser. No. 190,432 15 Claims. (Cl. 318--202) The present invention relates to an apparatus for selective transmission of any of a plurality of control signals over one transmission line together with receiving means coupled to the transmission line and responsive to the respective control signals to carry out respective control functions. The invention particularly relates to signal transmission by means of pulses taken from a conventional alternating current electrical power supply rather than from special pulse or carrier signal generating equipment as has been used in the past for the selective transmission of a plurality of signals.

An important application of the present invention is to the control of overhead travelling cranes or other similar apparatus. Various types of cranes involve a hoist trolley or the like which is transversely movable along a bridge like structure and which includes an electric motor, for example, to be controlled in any position of the trolley from a transversely [fixed control station. Normally, the control station is electrically connected with the hoist trolley by means of a substantial number of cross conldu'ctors. By way of example, in the case of a wound rotor reversible motor, six cross conductors have been required to control the acceleration and direction of rotation of the motor. A practical means for reducing the number of cross conductors required for this type of crane apparatus has been sought for a long time.

It is therefore an important object of the present invention to provide a relatively simple and inexpensive apparatus for the selective transmission of several control signals over a single transmission line which utilizes pulses taken from a conventional alternating current electric power supply rather than from special pulse or carrier signal generating equipment.

It is a further important object of the present invention to provide a system which reduces the number of cross conductors required tor crane bridges and similar equipment.

A more specific object of the present invention is to provide a crane motor control system utilizing a pair of cross conductors for controlling forward and reverse energization of an electric motor or the like at a plurality of different acceleration settings or a plurality of electrical motors with one or two different speeds in each direction, etc.

Other objects, features and advantages of the present invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which the single figure shows an exemplary electric control system in accordance with the present invention specifically adapted for controlling operation of a crane trolley drive.

In the illustrated embodiment, a reversible three phase excited wound rotor induction motor is illustrated for operation in forward and reverse directions of rotation under any one of cfilve acceleration conditions. By way of example the motor 10 may be associated with a movable carriage or trolley which is diagrammatically represented by dash line 11. The trolley 11 may be transversely movable along the bridge like structure of an overhead crane, for example. The crane bridge may have a transversely fixed cab or control station which is rep-resented by the dash line 12. In such a crane, the trolley 11 is movable transversely relative to the control 3,270,263- Patented August 30, 1966 station 12 while the carriage and control station may both move fjlOlIllZly in a longitudinal direction along with other parts of the crane bridge structure. By way of example, the reversible motor 10 may control the raising and lowering of a cable which is to be coupled to a load to be transferred by the crane.

Referring to the details of the electric control circuit for the motor 10, it will be observed that a series of forward contacts F1, F2, F3 control the forward energizas tion of the motor 10 from a three phase power supply 14, while reversing contacts R1, R2, R5 control reverse enengization of the motor 10. A forward mode electrically actuated contactor has a coil P which is coupled to the contacts F1, F2 and F6 and which causes closure of said contacts upon energization thereof. Similarly a reverse mode electrically actuated contactor has a coil R which is coupled to contacts R1, R2 and R6 and which is effective to close these contacts upon electrical energization thereof.

As is well known in the art, the speed of rotation of the motor 10 may be progressively increased by progressively decreasing the resistance in the rotor circuit. A series of twelve resistance elements designated by the reference numeral 15 and specifically identified by reference characters 15a-15l has been illustrated in association with successive pairs of contacts 1A1, 1A2; 2AI1, 2A2; 3A1, 6A2; and 4A1 and 4A2 for progressively reducing the resistance in series with each of the rotor windings of the motor. A three phase rotor winding is contemplated in the illustrated embodiment. The respective sets of contacts are controlled by coils 1A, 2A, 3A and 4A of respective acceleration controlling contactor-s and the respective contacts remain opened until the coil of the corresponding contactor is electrically energized. The resistors 15 are preferably external to the rotor which is diagrammatically indicated at 10a and suitable slip rings or the like may connect one terminal of each rotor winding to one of the terminals 15m, 15a and 15p of the resistance network. If the three rotor windings have their other terminals connected together to form a Y connection, then two groups of resistors (such as 15a, 15d, 15g, 15 and 15e, 15f, 15i, 15!) are initially connected in series with each pair of rotor windings of the Y.

The actuating circuits for the contactor coils F, R, 1A, 2A, 3A and 4A are shown as being controlled by relay contacts including normally closed contacts 01, R4, A2, F4, D2 and B2 and normally open contacts D1, A1, B1, C2, A3, C3, A4, C4, B3 and D3. The contacts C1 through C4 are actuated by means of a relay which when energized opens contacts C1 and closes contacts C2, C3 and C4. The actuating coil of the C relay has been assigned the reference numeral 92 and the letter C is used generically to designate related aspects of the circuitry including coil 92, the negative half cycles of waveform 108 and contacts 33, 34 and 35 of the master selector switch which control energization of the C relay. The same procedure has been followed for relays A, B and D. Contacts A1 through A4 are controlled by the actuating coil of the A relay which is assigned reference numeral and which when energized closes contacts A1, A3 and A4 and opens contact A2. Contacts B1, B2, B3 are controlled by the B relay coil designated by reference numeral 91 which when energized closes contacts B1 and B3 and opens contact B2. Relay contacts D1, D2 and D3 are controlled by the D relay coil which is assigned reference numeral 93 and which when energized causes the closure of contacts D1 and D3 and the opening of contacts D2. Energization of [forward mode contactor coil F opens contacts F4 and energization of reverse mode contactor coil R opens normally closed contacts R4. Energization of time delay relay 1T causes closure of normally open contact 1T1 after a predetermined time delay, ener-gization of time delay relay 2T causes closure of contact 2T1 after a predetermined time delay, and energization of time delay relay 3T causes closure of contact 3T1 after a predetermined time delay. The time delays introduced by relays 1T, 2T and ST are such as to insure smooth operation of the motor 10 during acceleration of the motor up to a desired operating speed.

The following tables summarize the various modes of operation in the forward and reverse directions.

TABLE I.FORWARD OPERATION Controlling Contacts Acceleration Relays Cont-actors Mo e Energized Energized I Normally Normally Open Closed 1 D F D C1, R4. F D1 or AL... 01, R4.

TABLE II.REVERSE OPERATION Controlling Contacts Acceleration Relays Contactors Mode Energized Energized Normally Normally Open Closed 1 B B1.. A2, F4. B1 or O2 A2, F4. 7 B, C- C B2. B2. F4.

4 C, D B2. B2. C4, D3, 2T1. C4, D3, 2T1. C2

In acceleration mode 1 in either direction of operation, all twelve of the resistors 15 are in circuit with the rotor windings of the motor 10. In mode 2, contacts 1A1 and 1A2 .are closed to short circuit the last three resistors 15a, 15b and 15c. In acceleration mode 3, contacts 2A1 and 2A2 are closed in effect disconnecting six resistors 15a through 151 from the rotor windings of motor 10. In acceleration mode 4, contacts 3A1 and 3A2 are closed by-passing resistors 15a through Hi, and in acceleration mode 5, contacts 4A1 and 4A2 are closed effectively disconnecting all twelve of the resistors 15 from the rotor windings and connecting the terminals 'of the rotor windings directly to each other without sub 'B, C and D energized and the time elapsing after such energization, the motor 10 will be operated at one of five acceleration modes in the forward or reverse direction. It will be observed that forward acceleration mode 5, for example, is obtained by energization of relays A and B after the time delay required for closure of contact 3T1 by timing relay 3T.

Thus, the possible modes of operation correspond to nine possible positions of a manual selector switch and this has been represented at the lower part of the drawing by positions off, 1-4 forward and 1-4 reverse for a sliding contact bar 20. The moving contact bar 20 is adapted to slide bodily in opposite lateral directions as indicated by the double headed arrow 21 to bridge between a common contact strip 22 which is continuously in electrical connection with the slide bar 20 and any of the stationary contacts 30-41. Thus in the forward No. 1 position, contact bar 20 connects stationary contact 40 with the common contact 22; in the forward No. 2 position, bar 20 connects common contact 22 with stationary contacts 38 and 39; in the No. 3 position, common bar 20 connects common contact 22 with stationary contact 37; and in forward position-No. 4, stationary contacts 30' and 36 are connected to the common contact 22. Similarly in the reverse mode, in position No. l'of the contact bar 20, contact 31 is connected to the contact 22; in mode No. 2, contact bar 20 connects stationary contacts 32 and 33 with common contact 22; in mode No. 3, stationary contact 34 is connected with common contact 22; and in mode No. 4 contacts 35 and 41 are connected with contact 22. The bar 20 together with the cooperating contacts may represent a master controller of a suitable conventional type for interconnecting the contacts by progressive rotary or linear movement in each of respective opposite directions.

It will be apparent by reference to the foregoing Tables I and II that if the contacts 30-32 control an energizing circuit for relay B, contacts 33-35 control an energizing circuit for relay C, contacts 36-38 control an energizing circuit for relay A and contacts 39-41 control an energizing circuit for relay D, the successive positions of the bar 20 will correspond to the desired modes of operation of the motor 10. Where, however, the master controller switch 20 is located at a control station such as indicated ,at 12 while the relays A-D and associated control circuitry are associated with a movable drive location such as crane bridge trolley 11, it is apparent that the use of individual cross conductors for coupling the respective series of contacts with the relays A-D would introduce a substantial complexity into the crane bridge construction which is undesirable. By the present invention, it is possible to utilize a single common conductor designated by the reference numeral 50 in place of the four cross conductors which would normally be required in a system such as represented in the drawings.

The present invention provides a control apparatus which encodes electrical pulses for transmission over the single common conductor 50 in such a manner as to represent at the output of a receiving means the signals that are normally sent over several conductors. The pulses are taken from the normal alternating electrical power supply such as indicated at 14 rather than from special pulse or carrier signal generating equipment as has been used in the past for selective transmission of a number of signals over a common transmission line.

. Thus there are no adjustments required for different voltage levels or for tuning to different frequencies.

In the illustrated embodiment a control transformer 60 is coupled to a single phase of the power supply 14 by means of conductors 61 and 62 and produces at its sec ondary winding sections 65 and 66 respective alternating current waveforms 67 and 68 which are substantially out of phase as measured with respect to a common return wire or ground designated by the reference numeral 70. The control transformer 60 thus is capable of supplying four pulse signals in each cycle of the supply current which may be selected by means of rectifiers 81, 82, 83 and 84 in conjunction with the master selector switch 20 for transmission over the common transmission line 50. More specifically, if the supply frequency is assumed to be 60 cycles per second, the waveform 67 will supply a positive half wave pulse A in the first half cycle extending from time 0 to time A second and will supply a negative half wave pulse D in the next half cycle between time second and second. The positive polarity half wave pulse A would be delivered via diode 81 to the A contacts 36-38 while the negative half wave pulse D in the second half cycle would be delivered via diode 82 to the D contacts 39-41. Similarly with respect to waveform 68, the negative pulse C in the first half cycle occurring between time 0 and second would be deliverer via diode 84 to the C contacts 3335 while the second positive polarity half wave pulse B occurring between time 34 and second would be delivered via diode 83 to the B contacts 30-32 of the master switch.

The circuitry is such that the first positive polarity pulse A of waveform 67 if transmitted to conductor 50 would serve to actuate the actuating coil 90 of relay A, the positive polarity pulse B occurring in the second half cycle of waveform 68 would serve to energize actuating coil 91 of relay B, the negative pulse C occurring in the first half cycle of waveform 68 would serve to energize the actuating coil 92 of relay C, and the negative polarity pulse D occurring in the second half cycle of the waveform 67 would serve to energize the actuating coil 93 of relay D. For convenience, this significance of the successive half-wave pulses of the waveforms 67 and '68 has been indicated by placing the corresponding letters A-D in association with the pulses.

Thus in the forward No. 1 position of bar 20, rectifier 82 would deliver a series of half wave negative polarity pulses such as indicated by the letter D associated with the Waveform 67 at alternate half cycles of the waveform. In position No. 2 in the forward mode, bar 20 would couple not only the D pulses of waveform 67 but also the positive polarity A pulses to the common conductor 50 linking control station 12 with the trolley 11 of the crane bridge. In position No. 3 in the forward mode, the A pulses of positive polarity of the waveform 67 only would be delivered by the bar 20 to the common conductor 50. In the No.4 forward position, the positive polarity pulses A of waveform 67 would be transmitted in the successive first half cycles and the positive polarity pulses B of the waveform 68 would be transmitted in the successive second half cycles of the supply.

With operation in the reverse mode, the No. 1 position of the bar 20 would supply positive pulses B of waveform 68 only to the conductor 50, while the No. 2 position would supply both the negative polarity pulses C and the positive polarity pulses B of the waveform 68 to the conductor 50.

In position No. 3 in the reverse mode, the negative polarity pulses C occurring in the successive first half cycles of waveform 68 would be transmitted to the common conductor 50. In position No. 4, the negative polarity pulses C of waveform 68 and the negative polarity pulses D of waveform 67 would be transmitted via the conductor 50 to the crane trolley.

It will be observed by reference to Tables I and II that the desired operation of the motor will be obtained providing a succession of positive polarity pulses A Will maintain relay A actuated, a series of negative pulses D of waveform 67 is effective to maintain relay D operated, a series of negative polarity pulses C of waveform 68 is effective to maintain relay C operated and a series of positive polarity pulses B of waveform 68 is effective to maintain relay B operated.

For decoding the pulse signal transmitted by means of the conductor 50, 'a second control transformer 100 is provided at the crane trolley 11 which is energized from the same phase of supply 14 via conductors 101 and 102.

The secondary sections of the control transformer 105 and 106 thus provide alternating current waveforms 107 and 108 which are precisely in phase with waveforms 67 and 68 respectively. For convenience, the successive half wave pulses have been designated by the same reference letters as for waveforms 67 and 68. The coils -93 of relays A-D are normally held at or near zero voltage by a balanced circuit configuration including resistors 121424 and rectifiers 131138. The rectifiers and resistors are utilized to detect the polarity and phase of the pulse waveform transmitted by the conductor 50. As indicated the transformers 60 and are connected to the same power supply with proper phasing so that terminals 65a and a are positive-going at the same time. All voltages refer to the common return wire 70 which connects the center taps and 141 of the secondaries of transformers 60 and 100.

Under a no signal condition with the master switch bar 20 in the central off position shown, current flows from the terminal 105a of secondary section 105 through conductor 144, through resistor 121 and through rectifier 132 to the common line 145, then through rectifier 138 and resistor 124 to conductor 146 which leads to the terminal 106a of transformer 100. The resistors 121 and 124 are of equal value and have equal voltage drops thereacross causing line to be held at or near zero voltage, that is near the voltage of the center tap 131 of transformer 100. The potential of point 150 between resistor 121 and diode .132 is at zero plus the forward voltage drop across diode 132 which represents an insufficient voltage to effect operation of relay coil 90 of relay A through diode 131. A half cycle later, when transformer terminal 105a is negative, current is prevented from flowing through relay coil 90 of relay A by the blocking effect of diode 131. A corresponding analysis applies to each of the other relay coils 91, 92 and 93.

By way of example, with the switch bar 20 in the No. 3 forward position, a circuit is completed for A pulses of waveform 67 from the secondary 65 via conductor 160, diode 81, stationary contact 37, switch bar 20, contact strip 22, and conductor 50 to wire 145. These positive pulses A of waveform 67 flow along the conductor 145 and through diode 134, resistors 1-22 and 121, diode 131, coil 90 of relay A, line 161 to line 162 which connects with the center tap 141 of the secondary of transformer 100 and with return conductor 70.

It will be observed that, effectively, the A positive pulse of waveform 107 is in aiding relation to the pulse A of waveform 67 with respect to coil 90 of relay A, while the pulse C of waveform 108 tends to drive point 163 between resistors 123 and .124 to a negative voltage condition relative to center tap 141 so as to block energization of coil 91 of relay B by the positive pulse A of waveform 67. In effect, it can be stated that the pulse C of Waveform 108 drives point 163 between resistors 123 and 124 to a negative voltage relative to line 161 preventing the forward conduction of diode 135 associated with relay coil 91 of relay B.

It will be apparent that the relays A-D must be of the type which are operated by half-wave rectified 60 cycle current so as to maintain their contacts continuously in an actuated condition without chattering. In effect a time delay in release of the relays of the order of second should be provided so that the successive unidirectional pulses will maintain the relays continuously in the actuated condition.

It will be apparent that in addition to actuation of the coil 90 of relay A, a type D pulse of waveform 67 or a type B pulse of waveform 68 may be transmitted to line 50 during the second half-cycle. Also the type A, B, C or D type pulse may be transmitted alone. A type C pulse in the first half cycle may be combined with a type B or type D pulse in the second half cycle. The resultant possible combinations are those tabulated in Tables paratus in a conventional manner.

, tively.

' cated at 70. The operating sequence for the movable bar 20 is arranged to produce a different combination of signals for each mode of operation. The relay panel including relays A-D at the receiving end has its contacts interconnected so as to present circuits to external control apparatus which are directly useable by that ap- The relay panel or phase and polarity detecting system at the receiving end has been designated generally by the reference numeral 190.

Summary of Operation In operation of the illustrated embodiment, single phase current of coordinated phase is supplied to the control transformer 60 at the control station 12 of the crane bridge and to the control transformer 100 of the crane bridge trolley 11 to generate corresponding waveforms which are substantially 180 out of phase as represented diagrammatically by waveforms 67, 68, 107, 108 in the drawings.

The master switch 20 beginning in the off position shown may be first moved to the left through the forward positions 1, 2, 3 and 4 to bring the motor up to speed in the forward direction. At position No. 1 of the bar 20 in the forward direction, pulse producing means comprising secondary 65 of transformer 60 and unidirectionally conductive means 82 selects a series of negative polarity pulses D of waveform 67 occurring in the successive second half cycles of the waveform for transmission over the single conductor 50 to the receiving relay panel 190 which is responsive to the negative polarity pulses D in the second half cycle of the Waveform 67 to energize coil 93 of relay D. In the No. 2 forward position of bar 20, both the positive polarity pulses A and the negative polarity pulses D of the wave 67 are transmitted over the common conductor 50 and are effective to maintain actuated relays A and D respec- In the No. 3 forward position, only the A relay is actuated while in the No. 4 forward position relay A remains actuated and the B pulses of waveform 68 are also transmitted over the common conductor 50 so as to actuate the B relay along with the A relay.

be deenergized as the bar 20 moves to the No. 3 position,

relay D will be energized in the No. 2 position and relay A will be deenergized when the bar reaches the No. 1 position, all of the relays being deenergized in the off position shown. of the motor 10 until the motor is brought to a stop when the bar 20 reaches the neutral position.

Similarly as the bar 20 is moved in the opposite direction to the No. 1 reverse position, B pulses of waveform 68 will be transmitted to the common conductor 50 to energize the B relay of panel 190 and begin drive of the motor 10 in the reverse direction. As the bar is moved to the No. 2 reverse position the C relay will also be energized. In the No. 3 position, the B relay is deenergized, and in the No. 4 position the C relay along with the D relay will be energized. This combination of steps corresponds to the progressive acceleration of the motor 10 in the reverse direction as summarized in Table II supra. Similarly when the bar 20 is moved from the No. 4 position to the zero position, the motor 10 will be progressively decelerated as the different combinations of relays come into operation in reverse order.

This will effect a progressive slowing The bar 20 in practice may be of a width in the direction of arrow 21 slightly greater than the spacing between successive contacts such as 39 and 40, 37 and. 38, 36 and 37, 31 and 32, 33 and 34, and 34 and 35, so as to provide a smooth transition between successive accelerating positions. Thus contact 39 will be engaged by bar 20 before disengagement with contact 40, so that relay D will be continuously in actuated condition as the bar 2? moves from forward position No. l to forward position No. 2.

By way of example, relays A, B, C, and D having actuating coils -93 and contacts Al-A4, B1-B3, C1- C4 and D1-D3 may be of the D.-C. type with a conducting ring around the core to maintain a magnetic field by inductive action during magnetic decay. On the other hand, it can be a relay of more conventional construction and with the magnetism retained by use of an appropriately sized capacitor connected in parallel with the coil to supply coil current during second periods between pulses. An example of the ring-type relay which is commercially available is the Westinghouse Class 16- 325 Type AZ relay. The parallel capacitor arrangement may use a 2 microfarad capacitor in parallel with the volt 60 cycle coil of a Cutler-Hammer Bulletin 957H2250 Type 300 relay.

While the specific example illustrated in the drawings involves control of a single motor in nine modes of operation, any number of motors or other devices can be controlled in one or two directions of motion in any number of speeds up to a total number of nine modes for the several motors, speeds, and directions in com bination, all using the single-phase transformer arrangements described in detail. A three-phase arrangement with phase displacement can control many more total modes for combinations of several motors, speeds, and directions.

In addition a commercial two-phase power supply can be used with two-phase control transformers to supply eight pulse trains of 90 degree phase displacement including the positive and negative polarities, each pulse having a useable duration of 90' degrees of power supply frequency.

In addition, a commercial three-phase, power supply can be used with three-phase control transformers to supply twelve pulse trains of 60 degree phase displacement including the positive and negative polarities, each pulse having a useable duration of 60 degrees of the power supply frequency.

Additional control systems may be linked to the movable station 11 by single conductors since return conductor '70 may be used for the additional systems as well as for the system associated with conductor 50.

The present invention thus contemplates a control apparatus for transmission over the single common conductor 50 in such a manner as to represent at the output of a receiving means the signals that are taken from the normal alternating electrical power supply such as indicated at 14 rather than from special pulse or carrier signal generating equipment as has been used in the past for selective transmission of a number of signals over a common transmission line. Thus there are no adjustments required for different voltage levels or for tuning produced by rectification of single phase, two phase or multi-phase alternating current and to similar or equivalent waveforms produced from an alternating current supply which are capable of being segregated at a receiving station.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

I claim as my invention:

1. A control apparatus comprising a number N of electrically actuated devices with the number N equal to at least two,

a corresponding number N of unidirectional pulse producing means for energization from a common alternating current supply and for producing respective unidirectional pulse waveforms in each cycle of the common supply which are distinct from each other in at least one of the electrical characteristics polarity and phase,

a common conductor for transmitting any of the number N distinct unidirectional pulse Waveforms generated by said pulse producing means,

means for selectively producing effective coupling between any of said number N unidirectional pulse producing means and said common conductor to effect transmission of the corresponding unidirectional pulse waveform to said common conductor,

and

receiving means having means for synchronization thereof with said alternating current supply to enable discrimination between unidirectional pulse Waveforms of the same polarity but of different phase and coupled to said common conductor and to said number N electrically actuated devices for effecting actuation of a different one of said devices in response to transmission of each of the N distinct pulse waveforms to said common conductor.

2. A control apparatus comprising a number N of electrically actuated devices with the number N equal to at least two,

a corresponding number N of unidirectional pulse producing means for energization from a common alternating current supply and for producing respective unidirectional pulse waveforms in each cycle of the common supply which are distinct from each other in at least one of the electrical characteristics polarity and phase,

a common conductor for transmitting any of the number N distinct unidirectional pulse waveforms generated by said pulse producing means,

means for selectively producing effective coupling between any of said number N unidirectional pulse producing means and said common conductor to effect transmission of the corresponding unidirectional pulse waveform to said common conductor, and

receiving means having means for synchronization thereof with said common alternating current supply to enable discrimination of unidirectional pulse waveforms of the same polarity but of different phase and coupled to said common conductor and to said number N electrically actuated devices for effecting actuation of a different one of said devices in response to transmission of each of the N distinct pulse waveforms to said common conductor,

said pulse producing means comprising means for coupling to said common alternating current supply and for producing first and second alternating current waveforms of the same frequency as the supply but with substantially 180 difference in phase and unidirectionally conducting means for transmitting pulses of respective different polarities interposed between said coupling means and said common concuctor.

3. A crane control system comprising reversible multiple speed drive means,

a plurality of electrically actuated means controlling the speed and direction of operation of said drive means,

unidirectional pulse producing means for energization from a commercial frequency alternating current supply and having a plurality of outputs for supplying respective partial wave pulses comprising pulses of opposite polarity in each of a plurality of parts of a cycle of the supply to provide at least four different partial Wave pulses in each cycle,

a common conductor for coupling the outputs of said pulse producing means with said electrically actuated means, and

phase and polarity sensing means having its input coupled to said common conductor and having respective outputs coupled to said electrically actuated means for effecting actuation of a different one of said electrically actuated means in response to transmission of each of said four different partial wave pulses by said common conductor.

4. A control system comprising pulse producing means including means for producing alternating current waveforms of different phase and a plurality of unidirectionally conductive means for acting on each of the respective alternating current waveforms to produce a plurality of partial wave pulses differing in phase and polarity,

means coupled to said pulse producing means for selectively transmitting different combinations of said partial wave pulses, and

receiving means having means for synchronization thereof with said pulse producing means to enable discrimination between partial wave pulses of the same polarity but of different phase and coupled to said transmitting means and differentially responsive to the respective combinations of said partial wave pulses.

5. A crane control system comprising (a) reversible multiple speed drive means,

(b) a plurality of electrically actuated means controlling the speed and direction of operation of said drive means,

(c) unidirectional pulse producing means for energization from a commercial frequency alternating current supply and having a plurality of outputs for supplying respective partial wave pulses comprising pulses of opposite polarity in each of a plurality of parts of a cycle of the supply to provide at least four different partial wave pulses in each cycle,

(d) a common conductor for coupling of the outputs of said pulse producing means with said electrically actuated means, and

(e) phase and polarity sensing means having means for synchronization thereof with said commercial frequency alternating current supply and having its input coupled to said common conductor and having respective outputs coupled to said electrically actuated means for effecting actuation of a different one of said electrically actuated means in response to transmission of each of said four different partial Wave pulses by said common conductor.

6. A control apparatus comprising (a) a number N of electrically actuated devices with the number N equal to at least two,

(b) a corresponding N of unidirectional pulse producing means for energization from a common alternating current supply of commercial frequency and for producing respective pulse Waveforms in each cycle of the common supply which are distinct from each other in at least one of the electrical characteristics polarity and phase,

(c) a common conductor for transmitting any of the number N distinct pulse waveforms generated by said pulse producing means,

(d) means for selectively producing effective coupling between any individual one of said number N unidirectional pulse producing means and said common conductor to effect transmission of the corresponding pulse waveform to said common conductor and for selectively producing effective coupling between a plurality of said number N unidirectional pulse producing means and said common conductor to effect transmission of the corresponding pulse waveforms to said common conductor, and

(e) receiving means having means for synchronization thereof with said common alternating current supply and coupled to said common conductor and to said number N electrically actuated devices for effecting actuation of individual ones of said devices in response to transmission of the respective ones of the N distinct pulse Waveforms to said common conductor for effecting actuation of a plurality of said devices in response to transmission of a corresponding plurality of the N distinct pulse waveforms to said common conductor.

7. The control apparatus of claim 6 with (a) said receiving means exclusive of said synchronization means consisting essentially of half wave rectifiers and resistance means connected in circuit with said synchronization means and said common conductor for blocking pulse waveforms of one polarity from each of the electrically actuated devices and for blocking actuation of each of the electrically actuated devices by a pulse waveform of predetermined phase relation to said common alternating current supply.

8. A control system comprising (a) pulse producing means including means for producing alternating current waveforms of different phase and a plurality of unidirectionally conductive means for acting on each of the respective alternating current waveforms to produce a plurality of unidirectional partial Wave pulses'difiering in phase and polarity,

(b) means coupled to said pulse producing means for selectively transmitting individual ones of said partial wave pulses as a train of pulses having a time period corresponding to the time period of the associated alternating current waveform and for selectively transmitting a plurality of partial wave pulses as superimposed trains of non-interfering pulses, and

(c) receiving means having means for synchronization with said pulse producing means and coupled to said transmitting means and operative to segregate each of the individual trains of partial wave pulses when transmitted individually and when transmitted as superimposed trains of pulses and said receiving means comprising polarity sensitive means for transmitting partial wave pulses of only one polarity and partial wave pulse producing means for generating partial wave blocking pulses for blocking trains of pulses of predetermined phase.

9. The control system of claim 8 with (a) said receiving means exclusive of said synchronization means consisting essentially of half wave rectifiers and resistance means connected in circuit with the synchronization means and with the transmitting means.

10. The method of transmitting signal information which comprises (a) converting an alternating supply current of commercial frequency to a plurality of alternating cur rent waveforms of different phase,

(b) selectively transmitting individual trains of unidirectional partial wave pulses of said plurality of alternating current waveforms of individual polarity and phase to represent respective different signals and selectively transmitting different combinations of said individual trains of partial wave pulses of said pluralityof alternating current waveforms in superimposed non-interfering relationship to represent re spective further different signals, and

(c) generating corresponding phase and polarity trains of unidirectional partial wave pulses at a receiving station and segregating the transmitted trains of partial Wave pulses with the'assistance of said generated trains of partial wave pulses to detect each of the respective different transmitted signals.

11. A control apparatus comprising (a) first and second electrically actuated devices,

(b) first and second control transformers having respective first and second primary and secondary terminals,

(c) means for connecting the primary terminals of the control transformers to a common alternating current supply to provide outputs at the respective secondary terminals of the first and second transformers of the same frequency and of predetermined phase relation,

((1) first and second half wave rectifier means for transmitting half wave pulses of positive and negative polarity respectively,

(e) a common conductor,

(f) means for selectively connecting said first and second half wave rectifier means between the secondary terminals of said first control transformer and said common conductor to provide selectively a train of half wave actuating pulses of positive polarity at said common conductor and a train of half wave actuating pulses of negative polarity at said common conductor,

(g) first means connected to said common conductor and to the secondary terminals of said second transformer and responsive to positive polarity transmitted by said first half wave rectifier means to actuate said first electrically actuated device and operative to block half wave pulses of negative polarity and to block half wave pulses of positive polarity which are of different phase than said train of half wave actuating pulses of positive polarity to prevent actuation of said first electrically device, and second means connected to said common conductor and to the secondary terminals of said secondtrausformer and responsive to said train of half wave actuating pulses of negative polarity to actuate said second electrically actuated device and'operative to block half wave pulses of positive polarity and to block half wave pulses of negative polarity which are of a different phase than said train of half wave actuating pulses of negative polarity.

12. A control apparatus comprising (a) first, second, third and fourth electrically actuated devices,

(b) first and second control transformers having respective primary windings for receiving primary currents of predetermined phase relation and having respective first and second pairs of secondary winding sections with respective first and second common points therebetween which are electrically connected and with respective first and second pairs of secondary terminals which are of opposite instantaneous polarity with respect to said common points,

(c) first and second pairs of half wave rectifier means for transmitting half wave pulses of positive and negative polarity respectively,

((1) common conductor means,

(e) means for selectively individually connecting each of the half wave rectifier means of said first pair between one of the secondary terminals of said first pair of secondary terminals and the common conductor means and for selectively individually connecting each of the half wave rectifier meanskof said second pair of half wave rectifier means between the other of the secondary terminals of said first pair of secondary terminals and the common conductor means, and

( f) receiving means connected to the secondary winding sections of said second transformer and to the common conductor'means for actuating said first, second, third and forth electrically actuated devices in response respectively to a train of positive polarity pulses from the one of said secondary terminals of the first transformer, a train of positive polarity pulses from the other of said secondary terminals of the first transformer, a train of negative polarity pulses from the other of the secondary terminals of the first transformer and a train of negative pulses from the one of said secondary terminals of said first transformer.

13. A control apparatus comprising (a) first, second, third and fourth electrically actuated devices,

(b) a common conductor and a return conductor,

(c) first, second, third and forth sources of half wave rectified current referenced to said return conductor, the first and second sources being of positive polarity but 180 out of phase and the third and fourth sources being of negative polarity and 180 out of phase but synchronized with said first and second sources,

(d) selector means for selectively coupling individual ones of said sources with said common conductor and for selectively coupling a plurality of said sources jointly with said common conductor, and

(e) receiving means synchronized with said sources and connected with said common and return conductors for actuating the first, second, third and fourth electrically actuated devices respectively in response to coupling of said first, second, third and fourth sources respectively with said common conductor and for simultaneously actuating a plurality of said electrically actuated devices in response to connection of a corresponding plurality of said sources jointly with said common conductor.

14. The control apparatus of claim 13 with (a) said electrically actuated devices comprising relay means having a release time delay period substantially exceeding the time period of the half wave rectified current supplied thereto 'by the respective sources for continuous actuation thereof by said half wave rectified current while providing for release of said relay means in response to interruption of half wave rectified current from the corresponding source.

15. A control system comprising common power suppulse producing means connected with said common power supply means and comprising at least three two terminal rectifier elements, each having two and only two terminals, for supplying respective trains of unidirectional partial wave pulses differing in phase and polarity and each train of pulses being synchronized with said common power supply means and having .a repetition frequency equal to the output frequency of said common power supply means,

transmitting means coup-led to said pulse producing means for selectively transmitting each of said trains of pulses individually and for selectively transmitting different combinations of said trains of pulses simultaneously,

receiving means operating entirely at said output trequency of said common power supply means and coupled to said transmitting means for receiving said trains of pulses therefrom,

said receiving means having phase sensitive means differentially responsive to the respective trains of pulses and the respective combinations of trains of pulses to provide respective different outputs therefrom, and

means operating entirely [at said output frequency of said common power supply means for synchronizing said phase sensitive means of said receiving means with said common power supply means.

References Cited by the Examiner UNITED STATES PATENTS 2,883,597 4/1959 Eck 317-137 X 2,924,813 2/1960 Mcador 317-137 X 3,029,369 4/1962 Lang 3 l7137 X OTHER REFERENCES German printed application 1,125,038, March 1962.

ORIS L. RADER, Primary Examiner. C. E. ROI-IRER, J. C. BERENZWE-IG,

Assistant Examiners. 

15. A CONTROL SYSTEM COMPRISING COMMON POWER SUPPLY MEANS FOR SUPPLYING ALTERNATING CURRENT POWER OF AN OUTPUT FREQUENCY, PULSE PRODUCING MEANS CONNECTED WITH SAID COMMON POWER SUPPLY MEANS AND COMPRISING AT LEAST THREE TWO TERMINAL RECTIFIER ELEMENTS, EACH HAVING TWO AND ONLY TWO TERMINALS, FOR SUPPLYING RESPECTIVE TRAINS OF UNIDIRECTIONAL PARTIAL WAVE PULSES DIFFERING IN PHASE AND POLARITY AND EACH TRAIN OF PULSES BEING SYNCHRONIZED WITH SAID COMMON POWER SUPPLY MEANS AND HAVING A REPETITION FREQUENCY EQUAL TO THE OUTPUT FREQUENCY OF SAID COMMON POWER SUPPLY MEANS, TRANSMITTING MEANS COUPLED TO SAID PULSE PRODUCING MEANS FOR SELECTIVELY TRANSMITTING EACH OF SAID TRAINS OF PULSES INDIVIDUALLY AND FOR SELECTIVELY TRANSMITTING DIFFERENT COMBINATIONS OF SAID TRAINS OF PULSES SIMULTANEOUSLY, RECEIVING MEANS OPERATING ENTIRELY AT SAID OUTPUT FREQUENCY OF SAID COMMON POWER SUPPLY MEANS AND COUPLED TO SAID TRANSMITTING MEANS FOR RECEIVING SAID TRAINS OF PULSES THEREFROM, SAID RECEIVING MEANS HAVING PHASE SENSITIVE MEANS DIFFERENTIALLY RESPONSIVE TO THE RESPECTIVE TRAINS OF PULSES AND THE RESPECTIVE COMBINATIONS OF TRAINS OF PULSES TO PROVIDE RESPECTIVE DIFFERENT OUTPUTS THEREFROM, AND MEANS OPERATING ENTIRELY AT SAID OUTPUT FREQUENCY OF SAID COMMON POWER SUPPLY MEANS FOR SYNCHRONIZING SAID PHASE SENSITIVE MEANS OF SAID RECEIVING MEANS WITH SAID COMMON POWER SUPPLY MEANS. 